Heat Sink by which potential energies entering
the system leave in degraded form according to
the second law of thermodynamics. Outflow is -kS.

Passive Storage of energy or materials in which
no new potential energy is generated. Work
must be done in moving the potential energy in
and out of the storage. This is called a
state variable with the sum of the inputs and
outputs being dQ/dt = J kQ.

Figure 5. (continued)

kJIJ2

Workgate. Intersection at which one flow
makes possible another. In this case one
flow affects the conductivity of the other
to produce a multiplier output, kJ1J2.

Workgate. Special case of the above where
temperature is used as a linear input.
Output is kJT.

Rate Sensor monitors flow rate and controls
input of another flow in proportion to
monitored flow.

Self-Maintaining Consumer uses its own
stored potential energy to do work on the
processing and work of the unit. An auto-
catalytic response through combination of
passive storage, workgate; can symbolize
an animal, city, industry, oyster reef
system, etc.

Special Case of self-maintenance that
adjusts inflow to depreciation.

Figure 5. (continued)

Flow a Squared Function from a passive
storage. Represents loss of potential
energy: eg, stress function such as
disease, or high energy cost of information
storage. Output is kQ2.

Logic Comparator with a critical threshold,
T; logic on or off control depends on which
input (+ or -) is larger

On-Off Switch to a flow.

Comparator-Switch Mechanism combines above
two components for switching action of flows
that control other flows: eg, switching
off flows of food, larvae, and salinity
when tide is out, on when it is in,

General Symbol for switching functions

the flow from the forcing functions off or on as water level changed.

Standing stocks included larvae biomass, oyster biomass, reef

structure, biomass of all organisms other than oysters, and diversity.

The shell portion of reef organisms is stored as reef structure, the

majority of which is oyster shell. Diversity is an information

storage of species per thousand individuals. Transfer of energy

between the forcing functions and the state variables occur along the

connecting pathways. Important natural processes such as a disease,

harvest, and feces and pseudofeces deposition are included in the

export pathways.

Increased temperatures accelerate respiration and stimulate food

flow through a workgate-sensor combination on the respiratory pathway.

This push-pull effect increases turnover times of storage and subse-

quently affects all other flows and processes in the system. Because

the temperature range at Crystal River is small, a linear temperature

action was used as an approximation,

METHODS

Field measurements were made of reef organism numbers and biomass,

reef metabolism and diversity, and "set" of oyster larvae

Biomass and Numbers

Measurements of biomass of oyster reef organisms from samples in

the discharge bay and control area were made during two seasons of the

year. A total of six biomass samples were collected in each area;

four summer samples and two winter samples. Duplicate samples were

taken from one reef in each area to check sampling variability.

Samples were selected from zones of highest organism density by a

random toss of a quarter meter square quadrant. One control sample

was taken from a lower density zone on a reef fringe. All organisms

and structure within the quadrant were removed to a depth of 10 cm,

transported to the laboratory and frozen consolidated. Samples from

which relationships of oyster weight and height were determined were

processed fresh. All conspicuous organisms from these samples were

counted, identified and weighed. Dry weights of organisms were taken

after one week at 105 C. Area-weighted values of oyster reef standing

crop calculated for each bay were used in the simulation models

Diversity

Number of species per thousand individuals as an indicator of

community diversity was determined by counting the first 1000 organisms

current speed fluoresceinn dye), and depth were also made with each set

of samples.

Channel Used to Measure Underwater Metabolism.
. and b. Photographs of reef 6, discharge bay,
July 7, 1974, at low tide.
Co and d. Photographs of reef 4, control area,
July 4, 1974, at high tide.
Note power plants in background,